package fr.in2p3.jsaga.helpers;
   
   import fr.in2p3.jsaga.Base;
   
   import java.io.*;
   import java.security.MessageDigest;
   import java.security.NoSuchAlgorithmException;
   
   /* ***************************************************
  * *** Centre de Calcul de l'IN2P3 - Lyon (France) ***
  * ***             http://cc.in2p3.fr/             ***
  * ***************************************************
  * File:   MD5Digester
  * Author: Sylvain Reynaud (sreynaud@in2p3.fr)
  * Date:   5 aout 2007
  * ***************************************************
  * Description:                                      */
  /**
   *
   */
  public class MD5Digester {
      public static boolean isSame(File refFile, byte[] data) throws IOException, NoSuchAlgorithmException {
          // compute MD5
          boolean same;
          byte[] md5 = MessageDigest.getInstance("MD5").digest(data);
          if (refFile.exists()) {
              byte[] ref = new byte[(int)refFile.length()];
              InputStream in = new FileInputStream(refFile);
              if (in.read(ref) > -1) {
                  same = equals(ref, md5);
              } else {
                  same = false;
              }
              in.close();
          } else {
              same = false;
          }
  
          // save MD5 to file
          OutputStream out = new FileOutputStream(refFile);
          out.write(md5);
          out.close();
  
          // debug
          if (Base.DEBUG) {
              File debugBaseDir = new File(refFile.getParentFile(), "debug");
              if (!debugBaseDir.exists()) {
                  debugBaseDir.mkdir();
              }
              File debugFile = new File(debugBaseDir, refFile.getName()+".xml");
              OutputStream f = new FileOutputStream(debugFile);
              f.write(data);
              f.close();
          }
          return same;
      }
  
      private static boolean equals(byte[] b1, byte[] b2) {
          if (b1.length != b2.length) {
              return false;
          }
          for (int i=0; i<b1.length && i<b2.length; i++) {
              if (b1[i]!=b2[i]) {
                  return false;
              }
          }
          return true;
      }
  }